In this paper age-to-age correlations for the body mass index and for skinfolds are evaluated for a sample of normal children studied from birth to adulthood. While correlations over larger age spans are modest, they become appreciable from childhood to adolescence and from adolescence to adulthood. Correlations are consistently higher for boys compared to girls, and only for the former does the body mass index correlate better than skinfolds. Significant correlations between weight increase in the first year and the adult body mass index were found, as well as between the age of 'adiposity rebound' and the adult body mass index. However, the small size of the correlations forbids any predictive applications. As it turns out, the individual prediction of the adult size of the body mass index or of skinfolds is a thorny problem, whatever variables and methods are chosen. The precision of such a prediction is very low up to late childhood and becomes somewhat better in adolescence. From a positive side, this leaves much room for overweight children to improve their state. On the other hand, the relative risk for becoming a heavy adult is much increased for those who are already heavy as children and adolescents. This underlines the dangers of early overweight from an epidemiological viewpoint.